Understanding the structure and properties of geological formations can reduce the cost of drilling wells for oil and gas exploration. Measurements made in a borehole (i.e., downhole measurements) are typically performed to attain this understanding, to identify the composition and distribution of material that surrounds the measurement device downhole. To obtain such measurements, magnetometers are sometimes applied to provide telemetry, ranging, and bit location functions.
Currently-available systems for calibrating magnetometers often include three-dimensional Helmholtz coils. However, such systems are often quite expensive. Accordingly, ongoing efforts are directed at reducing costs of magnetometer calibration systems while still maintaining quality, accuracy and sensitivity. Ongoing efforts are further directed at reducing errors that can be generated by Helmholtz coil-based systems.